Apparatus for drawing



March 3, 1936. c. B. CUSHWA 2,032,917

APPARATUS FOR DRAWING Filed NOV. 2, 1932 INVENTOR Maw 7 %m,Mz

Patented Mar. 3, 1936 UNITED STATES PATENT OFF-ICE APPARATUS FOR. DRAWING Charles B. Cushwa, Youngstown, Ohio Application November 2, 1932, Serial No. 640,823

3 Claims. (01. 205 1) My invention relates to the art of rolling and, in particular, to the rolling of seamless tubes by means of crossed rolls.

I am aware that numerous proposals have been made heretofore for the manufacture of seamless tubes by the use of crossed. rolls. All of these proposals with which I am familiar, have been characterized by the manufacture of a billet by rolling down an ingot, piercing the billet and rolling the pierced billet to reduce its wall thickness and increase its length. Methods of this character, obviously, are objectionable for the reason that they necessitate individual handling and treatment of each pipe length. The number of intermediate steps requires a large amount-0f apparatus and a considerable force of skilled men for proper operation thereof. It is an object of my invention to produce seamless tubes in continuous long lengths by reducing a hollow-cast ingot directly to its final tube form in one operation. In accordance withv my invention, I take an ingot cast hollow or tubular in shape, and dispose it uponv a suitable mandrel. The ingot is subjected to rolling between crossed rolls of novel form. I may use straight,

'cylindrical or tapered rolls and preferably the rolls have thread-like grooves formed at theentering end thereof to draw the ingot therebetween. The mandrel is supported against axial movement but is permitted to rotate with the ingot during cross rolling of the latter. Guide rolls may be used in addition to the crossed rolls for the purpose of maintaining the ingot,

in alinement. Adjacent the exit end of the crossed rolls, I may position a forming die. The throat of the die is dimensioned to finish the tube to its required external diameter. The die is supported for rotation and against axial movement.

The method of forming seamless tubes in accordance with my invention may take several different forms. I may start with a cylindrical ingot having the same external diameter as the tube to be formed, and an internal diameter con.- siderably less than that of the finished tube. In accordance with a variation of the method, the hollow ingot has an internal diameter equal to that of the finished tube, while the external diameter of the finished tube is somewhat greater than that of the tube. In the former case, the mandrel exerts a definite forming action on the tube, cooperating with the rolls. In the latter, the ingot slides along the mandrel without being deformed thereby, the deformation being effected by the rolls or the forming die, if used, and the mandrel serving merely to support the ingot internally during deformation and to size the finished tube to the proper internal diameter.

For a complete understanding of my invention, reference is made to the accompanying drawings illustrating a present prepared embodiment of apparatus suitable for carrying out the method, and certain modifications thereof.

In the drawings- The figure is a longitudinal sectional view, largely diagrammatic, with parts in section, showing a rolling mill designed. in accordance with the present invention, having an ingot in working position therein.

Referring in detail to the drawings, a rolling mill in accordance with my invention comprises a pair of straight cylindrical rolls 23 and 24, having the usual necks for mounting in bearings supported in any suitable housings. Since the construction of bearings and housings for crossed L rolls is already well known, more detailed description is unnecessary here. The rolls 23 and 2d are preferably adjustable vertically and laterally and are supported against axial thrust. The rolls are set at a slight angle of obliquity, as will be apparent in the figure.

A mandrel 25 having a plug 26 at the free end thereof is supported between the rolls 23 and 24 against axial movement by an abutment M which may be a part of the roll housing. The

mandrel '25 carries a removable collar I5 engaging the abutment. A thrust bearing [6 engageable with the collar 15 is removably secured to the reduced end of the mandrel by a nut H. The mandrel I2 is thus supported against axial movement but is able to rotate on its own axis.

Guide rolls (not shown) may be employed to cooperate with the forming rolls 23 and 24 and the mandrel 25 to maintain the ingot in alinement.

An ingot suitable for reduction in the mill shown is indicated at 3!. The ingot 3| preferably is of an external diameter substantially greater than that of the finished tube illustrated at the right of the plug 26 and indicated by the numeral 32. The internal diameter of the ingot is suflicient to permit easy clearance over the mandrel.

In the manufacture of seamless tube in accordance with my invention, by apparatus such as that shown, the ingot 3| is poured in any convenient manner and is heated in a soaking furnace to the proper rolling temperature. Several methods are already known for the hollow casting of ingots and it is not necessary to explain any particular method since the specific manner or means by which the hollow ingot is provided is not material to the present invention.

When the hollow ingot has been heated to the proper temperature for rolling, the nut I1 is removed from the reduced end of the mandrel 25 and the latter is, therefore, freed from the collar l5. The ingot is then slipped over the small end of the mandrel and this end is again secured to the abutment M by placing the collar l5 and roller bearings I 6 in position and applying the nut I! to the mandrel. With the mill in operation, the ingot is advanced toward the rolls by any suitable means. The leading end of the ingot is seized by the rolls, and because of their obliquity, is fed along the mandrel into engagement with the plug 26. In order to ensure forcible feeding of the ingot along the mandrel, I may provide thread-like grooves at the entrance end of the rolls l0 and H.

A die ring 21 is supported adjacent the exit ends of the rolls 23 and 24 on bearingrolls 28. The die ring 21 is supported against axial movement by an abutment 29 which may be a portion of the roll housing having a thrust bearing 30 seated therein for engagement by the annular face of the ring. The die ring 21 has a tapered bore extending therethrough which serves to form, reduce and draw out a tubular ingot 3| intoa finished tube 32. V

The ingot 3| has the same internal diameter as the finished tube 32. The external diameter of the ingot, however, is considerably greater than that of the tube to provide the metal required for forming a finished tube of considerable length. The ingot is centered with respect to the rolls as it slides axially of the mandrel and engages the plug 26. The rolls 23 and 24 having their axes at a slight angle, tend to force the ingot rearwardly of the mandrel and through the die ring 21.

Since the die ring 21 is rotatably supported by the rolls 28 and the bearings 30, it turns on its axis as the ingot isrotated by the rolls.23 and 24, the latter being driven in opposite directions. As the ingot is forced over the mandrel and through the ring, it is reduced and drawn out in the manner shown, into a continuous tube of considerable length.

; The die ring 2'! and the mandrel 26 are designed for only a single size of tube. Similar rings and mandrels of different dimensions will be provided for each different size of tube to bemanufactured.

. The mandrel 25 rotates during the rolling operation. There is substantially no circumferential movement of the ingot relative to the surfaces of the rolls, mandrel, plug and die ring. The ingot is fed axially of the rolls because of the obliquity thereof and is forcibly pushed over the mandrel and through the ring. The work on the ingot is thus all effected by sliding movement.

It will be apparent from the foregoing description 'of the apparatus and method which comprises. the invention, that seamless tube may be made in very long lengths by one operation upon a hollow ingot, without the additional expense and complications arising from the intermediate steps which are necessary under present methods. The continuous length of tube as it is delivered from the mill is preferably supported on a cooling bed where it may be sawed into the required lengths. Seamless tube may thus be made in as great lengths as permitted by transportation facilities, whereby the number of joints may be decreased over that necessary with the present lengths of tube. Since only one mill is required for forming the tube, the expense of installation and maintenance is correspondingly reduced. At the same time, a uniformity of product is assured because the operation is continuous and there is no possibility for working conditions to change materially from length to length of tube.

The invention described is characterized by numerous obvious advantages and desirable features, aside from the fact that the manufacture of seamless tube is facilitated and cheapened thereby. The number of operations heretofore thought necessary is considerably reduced with a consequent simplification of the actual method of manufacture, the avoidance of unnecessary handling of the product between the raw material and the finished article, and an increased rate of production, together with a smaller investment in machinery.

Although I have illustrated and described but one preferred embodiment of the invention, it will be apparent that variations in the manner and means herein described for practicing the invention may be resorted to, without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. Apparatus for making seamless tubes comprising a mill having rolls with their axes extending longitudinally thereof and at a small angle to each other, a rotatable mandrel extending between said rolls, means for supporting the mandrel against axial movement, a die ring adapted to embrace the end of the mandrel adjacent the exit side of the rolls, and means for rotatably supporting the ring against axial movement.

2. Apparatus for making seamless tube comprising a pair of rolls with their axes at a slight angle to each other, a mandrel extending therebetween, a thrust bearing adjacent one end of the rolls for rotatably supporting the mandrel against axial movement, a die ring adjacent the other end of the rolls substantially coaxial with said mandrel and embracing one end thereof, and a thrust bearing for rotatably supporting the ring against axial force.

3. Apparatus for making seamless tubes comprising a mill having at least two longitudinally extending rolls with their axes at small angles to each other, a mandrel adapted to lie between V the rolls for cooperation'therewith, one end of the mandrel extending beyond the ends of the rolls, a thrust bearing sustaining the mandrel against axial force but permitting free rotation thereof, a die ring embracing the end of the mandrel protruding from the rolls, and a thrust bearing supporting the ring against axial force while permitting free rotation thereof.

CHARLES B. CUSHWA. 

